South Oakleigh College ASTROPHYSICS: The Milky Way

Saturday, June 20, 2009

The Milky Way - Our Home Galaxy

The Milky Way galaxy is where our solar sytem is. It is believed to be a spiral galaxy similar to the one featured in the main picture heading this blogspot. It is believed to be 100,000 light years across, on average 1000 light years thick and estimated to contain more than 200 billion stars. If an imaginary model of the milky way were to be as big as the MCG (Melbourne Cricket Ground) then our solar system would be lmm across.

There are billions of galaxies in the Universe. The closest ones to the Milky Way include Andromeda and the Large and Small Magellanic Clouds. Androm

eda is 2.5 million light years away. The picture to the right is the Andromeda galaxy.

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AstroPhysics

Astronomy or Astrophysics is the scientific study of stars, planets, comets and galaxies. Astronomy is one of the oldest sciences when people sought to understand the bright lights in the night sky. The invention of the telescope enabled great progress to be made.

The scientific age began when Galileo Galilei , in Florence, Italy built a telescope similar to the design created by Hans Lippershey In 1610 Galileo published his findings that Jupiter had moons. As a result of Galileo's observations he theorised that the Sun is orbited by Earth and the planets. That the moon is not a planet but orbits the Earth. That Jupiter has its own moons. He challenged the belief that the Earth is the center of the Universe with all the planets, the Sun and the Moon and the Stars in orbit around around the Earth.
Galileo also used his telescope to discover that the Milky Way is composed of stars.

Modern telescopes on Earth have discovered a lot of other galaxies other than the Milky Way, during the 20th Century. It was Edwin Hubble who discovered in 1923, that galaxies exist outside of the Milky Way.

In 1990 a telescope, known as the Hubble Space Telescope, was launched into orbit around the Earth, 600km above the Earth and therefore above the Earth's atmosphere. Being above the atmosphere means that the images captured by the telescope are much clearer than are possible on the surface of the Earth, and therefore much more distant objects can be seen and analysed. Check out these sites [ http://hubblesite.org/ and http://hubble.nasa.gov/ ]